In conventional steel rolling lines, steel pieces such as billets, blooms and the like are rolled one by one and made to products. Recently, however, Japanese Unexamined Patent Publication Nos. 52-43754, 58-151971, 61-30287 and the like propose a method of subjecting a plurality of steel pieces such as billets and the like, which were extracted from a heating furnace, to flash butt welding and continuously rolling them to prevent the drop of a yield caused by the removal of the crop portions at the leading and trailing ends of the steel pieces and to increase productivity.
When steel pieces are welded to each other by flash butt welding, welding burrs are formed to them at the welded sections thereof by the flash and pressure applied thereto. Since the welding burrs are relatively large, they act as flaws in the rolling operation carried out thereafter. Thus, there is a possibility that a yield is lowered by the flaws, and when the steel pieces are wires and like, there is a possibility that they are broken at the portions of the flaws while they are rolled. Accordingly, the welding burrs must be perfectly removed before the steel pieces are rolled.
Japanese Unexamined Patent Publication Nos. 51-42040, 53-147649, 4-178273 and the like disclose burr removing apparatuses for a flash butt welder. However, any of the burr removing apparatuses proposed by them has a fixed-blade-type burr removing unit assembled therein for cutting welding burrs with a cutter fixed between a welder main body and a steel piece moving car so that the welding burrs can be cut just after a welding operation is finished because the cutting resistance of them is low at the time.
Further, Japanese Unexamined Utility Model Publication Nos. 59-176711, 61-199312 and the like disclose a rotary-blade-type burr removing apparatuses for removing a burr formed at an edge of a steel piece by pressing a rotatable circular cutting edge against the burr. However, in any of the fixed-type-blade and rotary-blade-type burr removing methods, when a stripe-shaped burr 3 formed across the surface of a steel piece 1 is cut along the burr using a cutter 5 as shown in FIG. 1, a protruding burr 4 is formed at an edge of the steel piece 1 although the cut burr 3 is removed to the outside of the steel piece 1 as a cut chip. Accordingly, a problem of the drop of a yield and the like described above is caused by the protruding burr 4 in the rolling operation carried out thereafter.